JP2003086900A - Semiconductor laser device and method for manufacturing semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser device in which irregularity of characteristic is restrained and yield is improved, and its manufacturing method. SOLUTION: The semiconductor laser device is so formed that a corner, which is formed of the end face of a semiconductor substrate and a plurality of crystal grown layers which is in the almost vertical direction relative to a linear active layer, and the top face of the plurality of crystal grown layers, is flatly formed except for a region comparatively near the active layer. As a form before bar cleavage, the semiconductor substrate has a V-shaped trench for guiding bar cleavage. The V-shape trench can be controlled with precision of photolithography. As a result, precision as a resonator length is suitably increased and cleavage is enabled. Cleavage is excellently performed by a depth of the trench and it is unnecessary to form a scripe trace, so that yield is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device using a side surface of a crystal growth layer as a mirror and a method for manufacturing the same, and more particularly to a semiconductor laser device suitable for shortening a cavity length and improving yield. It relates to a manufacturing method.

[0002]

2. Description of the Related Art A semiconductor laser device is incorporated in a module and is favored for optical communication because of its ease of handling. Unlike other semiconductor light emitting devices, the semiconductor laser device needs an optically flat surface to be used as mirror surfaces at both ends of the resonator. Therefore, the side surface of the element (a cleavage plane (cleavage plane)) that appears as a crack along the crystal orientation is usually used as the flat surface.

A conventional method of such cleavage will be described with reference to FIG. FIG. 8 is a diagram for explaining a conventional process when performing so-called bar cleavage. First, a wafer (semiconductor substrate 101) on which a crystal growth layer is formed is prepared, the lower surface side of the substrate is thinned by polishing or the like, and an electrode layer (not shown) is also formed on the lower surface (lower surface of the semiconductor substrate 101). . This state is shown in FIG. Figure 8
In (a), reference numeral 102 is a schematic drawing of an active layer, and a plurality of linear (striped) ones are further formed in parallel.

Next, as shown in FIG. 8 (b), a sharp blade with a thin blade edge such as a razor 103 is arranged along the plane direction (in this case, in the direction perpendicular to the linearly formed active layer). Press at an angle. Then, for example, when the semiconductor substrate is InP and the crystal growth layer is formed with the (100) plane as the main surface, as shown in FIG.
It is relatively easy to crack along the planes perpendicular to the (100) plane, such as the 1) plane and the (01/1) plane (where the / that precedes the 1 is the bar originally written on the 1 Means the same below.).

This method is widely known as cleavage, and since the surface obtained here is called a cleavage surface and is an optically flat surface, it has long been known as a method for obtaining a cavity facet of a semiconductor laser. It is used. It should be noted that lr in FIG. 8C is the resonator length, which is the length sandwiched between the cleavage planes. The cleavage at this stage is called bar cleavage because the shape after cleavage becomes a bar shape. Although not shown, after the bar cleavage, chip cleavage is performed so that the linear active layers 102 are included one by one in the direction perpendicular to the bar cleavage surface.

Another example of the conventional method of bar cleaving will be described with reference to FIG. FIG. 9 is a diagram for explaining another example of the conventional process when so-called bar cleavage is performed.
First, a wafer on which a crystal growth layer is formed (semiconductor substrate 10
1) is prepared, the lower surface side of the substrate is thinned by polishing or the like, and an electrode layer (not shown) is also formed on the lower surface (the lower surface of the semiconductor substrate 101).
To form. This state is the substrate 101 shown in FIG. In FIG. 9A, the same numbers are assigned to those already described.

Next, as shown in FIG. 9A, a scriber 121 is provided near the edge of the semiconductor substrate 101 on which the crystal growth layer is formed according to the cavity length setting in the direction perpendicular to the linear active layer 102. A scribe mark 122 is made by using. Then, the semiconductor substrate 101 is pressed so that the scribe marks 122 are aligned with the edges 134 of the triangular prism jig 133 having the acute-angled edges 134.
Apply pressure to both sides. As a result, as shown in FIG. 9C, a bar cleavage surface is obtained. Although not shown, after the bar cleavage, chip cleavage is performed so that the linear active layers 102 are included one by one in the direction perpendicular to the bar cleavage surface.

[0008]

In the conventional bar cleaving method as described above, the position where the cleavage line enters is determined by the position where the razor or scriber is inserted, so that the following inconvenience may occur.

That is, firstly, since the positioning accuracy of the razor and the scribe depends on the accuracy of the person or machine, the cleavage can be performed only with the accuracy according to them. Therefore, the characteristics of the manufactured semiconductor laser device vary. This variation becomes remarkable especially when the resonator length is shortened.

Secondly, the line for cleavage (cleavage line) may not mean a straight line but meander, depending on how mechanical force is applied. Therefore, the yield is reduced.

Thirdly, when the resonator length becomes short, it becomes difficult to break. Therefore, the yield is reduced.

Fourthly, the portion having the scribe traces cannot be used as a semiconductor laser device (device). Therefore, the yield is reduced.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor laser device capable of suppressing characteristic variations and improving yield, and a manufacturing method thereof.

[0014]

In order to solve the above problems, a semiconductor laser device according to the present invention comprises a semiconductor substrate,
A plurality of crystal growth layers stacked on the semiconductor substrate, wherein one of the plurality of crystal growth layers is formed in a linear shape having a thickness parallel to a surface of the semiconductor substrate. Is an active layer that is formed on the semiconductor substrate and the end faces of the plurality of crystal growth layers that are substantially perpendicular to the linear active layer and the top faces of the plurality of crystal growth layers. , And is removed in a planar shape except for a portion relatively close to the active layer (claim 1).

That is, "whether the end faces of the semiconductor substrate and the plurality of crystal growth layers in the direction substantially perpendicular to the linear active layer and the upper surfaces of the plurality of crystal growth layers should be formed relatively in the active layer. "Except for the near portion, it is removed in a plane" means that the semiconductor substrate on which the crystal growth layer is formed has a V-shaped groove that guides the bar cleavage as the shape before the bar cleavage. To do. The position of such a groove on the crystal growth layer side can be controlled by the accuracy of photolithography, which is widely used as a semiconductor manufacturing technique.

Therefore, it is possible to considerably increase the accuracy of the cavity length for cleavage, and it is possible to suppress variations in the semiconductor laser device. In addition, the cleavage is favorably performed due to the depth of the groove, and it is not necessary to make scribe marks, so that the yield is improved.

Further, in the method for manufacturing a semiconductor laser device according to the present invention, a step of forming a crystal growth layer including a linear active layer on the semiconductor substrate, the linear growth layer being substantially parallel to a surface of the semiconductor substrate, and the crystal. A step of intermittently forming a groove from a side of the crystal growth layer of a semiconductor substrate on which a growth layer is formed, avoiding the active layer in a direction substantially perpendicular to the linear active layer; and forming the groove. Along with the step of bar cleaving the semiconductor substrate having the crystal growth layer, and the step of chip-separating the bar cleaved semiconductor substrate having the crystal growth layer in a direction substantially perpendicular to the direction of the bar cleaving. It has (claim 7).

That is, a groove is intermittently formed from the side of the crystal growth layer of the semiconductor substrate on which the crystal growth layer is formed, avoiding the active layer in a direction substantially perpendicular to the linear active layer, and formed. Since the semiconductor substrate having the crystal growth layer is cleaved along the groove, the bar cleavage is guided to the groove and the yield is increased. Further, the position of such a groove on the crystal growth layer side can be controlled by the accuracy of photolithography commonly used as a semiconductor manufacturing technique.

Therefore, it is possible to considerably increase the accuracy of the cavity length for cleavage, and it is possible to suppress variations in the semiconductor laser device. In addition, the cleavage is favorably performed due to the depth of the groove, and it is not necessary to make scribe marks, so that the yield is improved.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a preferred embodiment of the present invention, in the semiconductor laser device according to claim 1, the plurality of crystal growth layers are formed by growing on the (100) plane of the semiconductor substrate. The surface that has been removed and appeared in the planar shape is the (11/1) surface or the (1/11) surface of the semiconductor substrate and the plurality of crystal growth layers. In a semiconductor substrate having a crystal growth layer grown and formed on the (100) plane of the semiconductor substrate, if a groove is formed before the bar cleavage, that is, if the crystal growth layer is etched with a predetermined mask using hydrochloric acid as an etching solvent. , V-shaped grooves are formed due to the plane orientation dependency. This V
The surface of the groove is the (11/1) surface or (1/1 /
11) The surface.

As a preferred embodiment of the present invention,
2. The semiconductor laser device according to claim 1, wherein the end surface side of the removed corner is 13 μm to 25 μm from the upper surface of the plurality of crystal growth layers. Lower limit 13 μm
Is a relatively thick dimension that is usually considered as the thickness of the semiconductor substrate (before bar cleavage) on which the crystal growth layer is formed 13
Even if it is set to 0 μm, it is the minimum value obtained by an experiment for forming a groove that easily breaks. The upper limit of 25 μm secures a space for forming a bonding pad for connecting a conductor wire of 40 μm square, which is the minimum possible, on the upper surface of the crystal growth layer even when the resonator length is set to 100 μm which is a relatively small dimension that is usually considered. Is the maximum to do.

As a preferred embodiment of the present invention,
The semiconductor laser device according to claim 1, wherein the shape of the removed corners of the plurality of crystal growth layers on the upper surface is substantially rectangular. Each of the intermittent grooves before cleaving the bar has a rectangular shape as a plane, and 1/4 of the upper, lower, left, and right divisions are allocated as the semiconductor laser device after the cleaving.

Further, as a preferred embodiment of the present invention,
2. The semiconductor laser device according to claim 1, wherein a shape of the removed corners on the upper surfaces of the plurality of crystal growth layers is a shape obtained by dividing a substantially isosceles trapezoid into halves in line symmetry. The shape of each of the intermittent grooves before the cleaving of the bar is a shape in which the long base sides of the isosceles trapezoids are back-to-back, and 1/4 of the upper, lower, left, and right divisions are allocated as the semiconductor laser device after the cleavage. It is a thing.

Further, as a preferred embodiment of the present invention,
2. The semiconductor laser device according to claim 1, wherein the semiconductor substrate is made of InP, and each of the plurality of crystal growth layers is made of InP or In _x Ga.
_1−x As _y P _1−y (0 <x <1, 0 <y ≦ 1). InP layer or In, Ga, As on InP substrate
In order to form a ternary crystal growth layer or a quaternary crystal growth layer of In, Ga, As, and P, it is one of the types that are normally used for communication purposes at present as a semiconductor laser device.

Further, as a preferred embodiment of the present invention,
The method for manufacturing a semiconductor laser device according to claim 7,
The step of forming a groove includes a step of forming a mask layer on the upper surface of the crystal growth layer in a pattern in which punching exists in a portion corresponding to the groove to be formed, and the crystal growth layer formed by the mask layer formed. And a step of removing the mask layer after the etching. By forming the mask layer, a predetermined groove is formed in the crystal growth layer. In addition to such a method of newly forming a mask layer, for example, the uppermost one of the crystal growth layers is formed in a pattern in which punching exists in a portion corresponding to a groove to be formed in advance, It is also possible to adopt a method of etching the crystal growth layer below it using this as a mask.

In the step of forming the mask layer, the punching shape may be substantially rectangular. Further, in the step of forming the mask layer, the punching shape may be a shape in which the sides of the long bases of the isosceles trapezoid are substantially back-to-back.
In either case, a V-shaped groove can be formed in the crystal growth layer (or over the semiconductor substrate) by etching.

Further, where the semiconductor substrate is made is InP, the plurality of crystal growth layer, each of the material is InP or _{In x Ga 1-x As y} P 1-y
(0 <x <1, 0 <y ≦ 1), and the step of etching the crystal growth layer is performed using a solvent containing hydrochloric acid as an etching solvent. InP layer on InP substrate, ternary system of In, Ga, As, or In, Ga,
A quaternary crystal growth layer of As and P is formed,
As a semiconductor laser device, it is one of the types usually used for communication applications at present. The InP layer can be satisfactorily etched by using hydrochloric acid as an etching solvent.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are views for explaining the first embodiment of the present invention. First, a semiconductor substrate 11 having a crystal growth layer including an active layer 12 as shown in FIG. 1A is prepared. The active layer 12 is formed in a straight line (stripe) shape parallel to the semiconductor substrate 11, and a plurality of active layers 12 are further formed in parallel. The semiconductor substrate 11 on which such a crystal growth layer is formed has a sectional structure as shown in FIG. 5, for example. FIG. 5 is a cross-sectional view showing an example of the semiconductor substrate 11 having the crystal growth layer including the active layer 12 shown in FIG.

Here, as a premise for explaining FIG. 1, the sectional structure shown in FIG. 5 will be described. To obtain the cross-sectional structure shown in FIG. 5, first, for example, n-type InP is used for the semiconductor substrate 11, and the InP buffer layer 52, the n-type InP clad layer 53, and InGaA are formed on the (100) plane.
The sP active layer 12 is sequentially crystal-grown on the entire surface. Then, the InGaAsP active layer 12 as a waveguide of the resonator laser is processed in a stripe shape in the (01/1) direction of the growth substrate 11 by using a photolithography process.

Subsequently, a p-type InP layer 55 and an n-type InP layer 56 are selectively formed on the right and left sides of the stripe-shaped waveguide, and a p-type InP clad layer 57 and a p-type InGaAs contact layer 58 are sequentially formed on the entire surface. To do. Note that p-type In
The GaAs contact layer 58 may be a quaternary system of In, Ga, As, and P, but a ternary system of In, Ga, As is generally used because the contact resistance is smaller.

The semiconductor substrate 11 shown in FIG. 1 (a) has a p-type I
A p-type electrode is formed on the nGaAs contact layer 58 (main surface), the back surface side of the substrate 11 is thinned by polishing or the like to a thickness that allows cleavage, and the n-type electrode is formed on the back surface. is there. The total thickness is, for example, 100 μm.
And the upper part of the InP buffer layer 52 is, for example, about 10 μm.

By the way, in the sectional structure shown in FIG.
A structure in which trenches are formed on both sides slightly away from the stripe-shaped active layer 12 for reducing the element capacitance is often used, but it is omitted here because it is not an essential item for implementing the present invention. Of course, the present invention can be applied even with such a groove.

In the semiconductor substrate 11 shown in FIG. 1A, the stripes of the active layer 12 are shown by solid lines on the main surface for simplification of the drawing. In this embodiment, next, FIG.
As shown in FIG. 3, the bar cleavage groove 13 is intermittently provided in the direction perpendicular to the stripes of the active layer 12 while avoiding the vicinity of the active layer 12, and the chip separation is intermittently provided in the direction orthogonal to the bar cleavage groove 13 while avoiding the vicinity of the bar cleavage groove 13. A plurality of grooves (chip cleaving grooves) 14 are formed in parallel with each other. The process of forming the bar cleavage groove 13 and the chip separation groove 14 will be described later.

Next, as shown in FIG. 1 (c), the back side of the bar cleavage groove 13 is pressed against the acute ridge line 16 of the triangular prismatic jig 15 to apply pressure to both ends of the substrate 11. Stress is concentrated in the bar cleavage groove 13 to perform cleavage. Then, the cleavage along the valley line formed at the bottom of the groove 13 advances along the groove 13 having a broken line, and a highly accurate cleavage surface (= resonator end surface) can be obtained.

The bar-shaped substrate thus obtained (see FIG. 2)
The detailed shape of the resonator end face in (a)) is shown in FIG.
As shown in (b). In FIG. 2B, the groove used for cleavage has a half shape at the center when separated, and has a flat slope 21 and a surface 24 facing the active layer 12.
And 25 are appearing. The inclined surface 21 terminates in the cutback line 22 on the main surface side and terminates in the cutback line 26 on the resonator end surface side. The above-mentioned surface 24 is a surface that falls in the vertical direction from the cut-back line 23 of the main surface, and the above-mentioned surface 25 is formed by cutting back from this surface 24 at an angle. The formation of these planes 21, 24 and 25 is the result of etching according to the plane orientation of the crystal growth layer.

Corresponding to the shape of the groove before being separated by cleavage, the slope 21 and the surfaces 24 and 25 described above are shown in FIG.
As shown in (c) and (d). That is, FIG.
FIG. 2C is a view of the surfaces 24 and 25 seen from a direction perpendicular to the surface 24, and FIG. 2D is a perspective view of the groove before being separated. As can be seen from FIG. 2D, the groove is a V-shaped groove, and is cleaved along the valley line 26 (corresponding to the turning line 26 after separation).

The bar-shaped substrate shown in FIG. 2A is further separated into chips by using the chip separation grooves 14. The present inventors have already proposed such element formation and have disclosed it in, for example, Japanese Unexamined Patent Publication No. 08-316570, and therefore will not be described in detail here.

In other words, in other words, the shape shown in FIG. 2B should be the end faces of the semiconductor substrate and the crystal growth layer, which are substantially perpendicular to the linear active layer 12, and the top face of the crystal growth layer. The corner is removed in a planar shape, and the shape of the removed corner of the crystal growth layer on the upper surface is substantially rectangular. This is because each of the intermittent grooves 13 before the cleavage of the bar has a rectangular shape as a plane, and as a semiconductor laser device after the cleavage of the bar and the chip separation, it is divided into 1/4 of the upper, lower, left and right parts thereof.
Four rectangles are assigned.

Although the bar cleavage groove 13 can be formed by etching at the same time as the chip separation groove 14 in the above, it may be formed separately in different processes.
When forming the grooves 13 and 14 at the same time, it is necessary to pay attention to the design of the width of the pattern serving as an etching mask. This is because the chip separation groove 14 can be formed mainly by a plane that falls vertically due to the plane orientation of the crystal growth layer, and the etching does not end due to the plane orientation like the V-shaped groove. That is, since the bar cleavage groove 13 is a V-shaped groove, its depth is generally shallower than the depth of the chip separation groove 14 in order to secure a space for forming a bonding pad for connecting a conductive wire on the main surface. Become. The pattern width for the chip separation groove 14 is selected so that the chip separation groove 14 is etched at least deeper than that, for example, until the formation of the V-shaped bar cleavage groove 13 is completed by etching.

In the semiconductor laser device obtained as described above, the bar cleavage groove 13 cleaves at a position as designed, and defects such as wavelength characteristics caused by unevenness of the cavity length are eliminated. The semiconductor laser device described above is
For example, it is mainly used by being incorporated in a communication module.

Next, an embodiment different from the above-mentioned embodiment will be described with reference to FIGS. 3, 4, 6 and 7. 3 and 4 are views for explaining the difference between this embodiment and the previous embodiment, and FIGS. 6 and 7 are process diagrams showing the formation of the bar cleaving groove in this embodiment.

Also in this embodiment, preparing a semiconductor substrate 11 having a crystal growth layer as shown in FIG. 1A is the same as in the previous embodiment. The sectional structure is as shown in FIG. 5 which has already been described.
Then, as shown in FIG. 1B, the bar cleaving groove 13 is intermittently provided in a direction perpendicular to the stripe of the active layer 12 while avoiding the vicinity of the active layer 12, and the bar cleaving groove 13 is orthogonal to the bar cleaving groove 13.
A plurality of chip separation grooves 14 are intermittently formed in parallel with each other while avoiding the vicinity.

Here, a method of forming the bar cleavage groove 13 will be described. As described above, the bar cleavage groove 13 is formed as one of the intermittent grooves in the portion corresponding to the region A shown in FIG. 5 so as to avoid the active layer 12. As a perspective view of the region A shown in FIG. 5 viewed from the direction B, that is, with the (011) face facing forward, FIGS. 6A and 6B show the process of forming the bar cleavage groove 13. 7 (a)
It is (b).

First, as shown in FIG. 1A, the entire surface (main surface) of the substrate 11 on which the crystal growth layer is formed, as shown in FIG.
As shown in (a), an insulating film 61 made of SiO ₂ is formed. Subsequently, as shown in FIG. 6B, the SiO ₂ film 61 is patterned so as to correspond to the planar shape of the groove to be formed. Such patterning can be made is removed by etching the SiO ₂ film 61 to form a mask layer which is similar patterned by a photolithography process on the SiO ₂ film 61 for example, ammonium fluoride.

Next, as shown in FIG. 7A, using the patterned SiO ₂ film 61 as a mask, for example, a sulfuric acid-based solvent or a bromine-based solvent is used to p-type InGaAs.
The contact layer 58 is removed by etching, and the mask pattern is transferred. Finally, using the p-type InGaAs contact layer 58 as a mask, the InP layers 57, 56, 55 and 5 are formed.
3, 52, 11 are etched with hydrochloric acid, for example (see FIG. 7).
(B)). The same applies when the p-type InGaAs contact layer 58 is a quaternary system of In, Ga, As, and P. Although not shown, the SiO ₂ film 61 is removed after the time when it is no longer required as a mask.

As shown in FIG. 7B, when etching is performed with hydrochloric acid using the InGaAs layer as a mask, the etching stops at a specific plane orientation, and etching is not performed any further. In this case, since the bar cleavage groove 13 was linearly formed in the (011) direction on the (100) surface, the surfaces forming the V-shape where the etching stops are the (11/1) surface and the (1/1 /) surface.
1) surface, and the cross-sectional shape of the bar cleavage groove 13 is shown in FIG.
As shown in, the shape is V-shaped (a triangle with a base on the top). The above-described process for forming the bar cleaving groove 13 is also performed in the above-described embodiment in a planar shape (SiO ₂
The same except for the shape in which the film 61 is patterned).

Here, the difference between the groove shape to be formed and the above embodiment will be described. 3 (a1), FIG.
(B1) is an observation of the mask pattern of the p-type InGaAs contact layer 58 for forming one of the bar cleavage grooves 13 in the above-described embodiment and this embodiment from the main surface of the substrate. In FIG. 3 (a1),
A rectangular mask is formed in advance so as to match the cutback lines 22 and 23. On the other hand, in FIG. 3 (b1) which is this embodiment, the mask is previously formed in a shape in which the long bottom sides of the isosceles trapezoid are back-to-back, whereby the longitudinal cut lines 31 and The cut line 32 in the lateral direction is formed on the main surface. The apex 33 is present in the cutback line 32, which is different from the previous embodiment.

FIGS. 3 (a2) and 3 (b2) show the shape of the bar cleavage groove obtained by etching according to the pattern of FIG. 3 (a1) and FIG. 3 (b1), respectively. It was observed from. As described above, in the bar cleaving groove shown in FIG. 3 (a2), which is the previous embodiment,
Near the end of the groove in the longitudinal direction, the valley line 26 terminates at the surface 25,
The valley line is further divided into two to form the end of the surface 25 (see also FIGS. 2 (c) and 2 (d)).

In the bar cleaving groove 13 of the previous embodiment having such a shape, according to the experiment, when the cleaving resonator length is further shortened, the cleaved position may deviate from the center of the groove. This is shown in FIG. Figure 4
FIG. 6 is a diagram for explaining how the cleavage lines 41, 42 are inserted by the bar cleavage groove, and the same portions as those already described are given the same numbers. It is considered that the deviation of cleavage as shown in FIG. 4A is caused by the valley line of the groove being divided into two at the end. That is, with such a valley line, when the cavity length is further shortened, stress concentration during bar cleaving is likely to occur at the intersection of the three surfaces 25, 24, and 21. It is considered that cleavage will occur on the surface that passes through.

On the other hand, the present embodiment shown in FIG.
In the bar cleaving groove shown in 2), near the end of the groove in the longitudinal direction,
The valley line 34 further extends straight toward the apex 33. That is, as can be seen from FIG. 3 (b3) which is a perspective view of the shape shown in FIG. 3 (b2), the V-shaped surface 35 is
Near the end of the groove in the longitudinal direction, the angle is changed by the cut-back line 36 to terminate at the cut-back line 32, but at the same time the valley line 34 is formed.
A cutting line is formed toward the apex 33 so as to extend.

In this embodiment having such an improved valley line, as a result of experiments, even if the resonator length is further shortened, as shown in FIG. It was found to be formed. It is considered that this is because the point where stress is likely to be concentrated, such as the intersection of the three surfaces, is eliminated as in the previous embodiment. In FIG. 4B, the same numbers are assigned to the parts already described.

As described above, in this embodiment,
Even if the cavity length is shorter, the bar-shaped cleavage is facilitated, and the semiconductor laser device as designed can be obtained with good yield.

Needless to say, in the above-described embodiment and this embodiment, the bar cleavage groove 13 must be formed in a broken line shape (intermittently avoiding the vicinity of the active layer 12). This is because it is necessary to use a cleaved facet for the cavity end face, and because the active layer 12 portion originally has an InGaAsP layer that cannot be etched with hydrochloric acid. Also,
It is more preferable that the bar cleavage groove 13 and the chip separation groove 14 do not intersect because the plane orientations that appear by etching are different, but they may also intersect. This is because it does not hinder the cleavage itself.

The depth of the bar cleaving groove 13 can be set by the width (length in the lateral direction) of the punched portion of the mask. This is because, as already described, the etching stops at a specific plane orientation, and etching is not performed any further. In both of the above embodiments, the angle of the V-shaped groove is about 100 degrees, and even when the resonator length is set to 100 μm, which is a relatively small dimension that is usually considered,
40 μm, which is the minimum possible value on the upper surface of the crystal growth layer
In order to secure a space for forming a bonding pad for connecting a square conductor wire, one of the guidelines is to set the depth to 25 μm or less. When the resonator length is 100 μm and the bar cleave groove depth is 25 μm, the length in the resonator length direction secured on the upper surface of the crystal growth layer is 100−2 · 25 tan (100
The calculated deg / 2) is about 40.4 μm.

Further, the semiconductor laser devices obtained in the above-described embodiments have a good appearance because the peripheral corners can be said to be beveled by etching, and further, the corners are missing in the work of handling chips when assembling as a module. This has the effect of avoiding problems that affect reliability. This is because when the corners are stretched, the chip is likely to hit a work jig such as a collet due to stress concentration during assembly.

In addition, not only the bar cleavage but also the chip separation (cleavage) uses the etching groove, so that all four sides observed from the upper surface of the chip are formed by etching. As a result, not only the above-mentioned dimensional accuracy and appearance, but also while forming the passivation film on the pn junction end face appearing around the chip to form the semiconductor laser device,
There is also an effect that this can be protected.

[0058]

As described in detail above, according to the present invention,
"Whether the end faces of the semiconductor substrate and the plurality of crystal growth layers, which are in a direction substantially perpendicular to the linear active layer, and the top faces of the plurality of crystal growth layers should be flat except for a portion relatively close to the active layer. The semiconductor substrate on which the crystal growth layer is formed has a V-shaped groove that guides the bar cleavage as a shape before the bar cleavage. Since the position of such a groove on the crystal growth layer side can be controlled by the accuracy of photolithography, which is widely used as a semiconductor manufacturing technique, it is possible to considerably increase the accuracy as a resonator length and cleave the semiconductor. Variations as a laser device can be suppressed. In addition, the cleavage is favorably performed due to the depth of the groove, and it is not necessary to make scribe marks, so that the yield is improved.

Further, according to the present invention, a groove is intermittently formed from the side of the crystal growth layer of the semiconductor substrate on which the crystal growth layer is formed, avoiding the active layer in a direction substantially perpendicular to the linear active layer. Then, since the semiconductor substrate having the crystal growth layer is cleaved along the formed groove, the cleaving is guided to the groove and the yield is increased. Further, the position of such a groove on the crystal growth layer side can be controlled by the accuracy of photolithography commonly used as a semiconductor manufacturing technique. Therefore, it is possible to significantly increase the accuracy as the cavity length and to perform the cleavage, and it is possible to suppress the variation as the semiconductor laser device.

[Brief description of drawings]

FIG. 1 is a diagram illustrating first and second embodiments of the present invention.

FIG. 2 is a continuation of FIG. 1 and is a diagram for explaining the first embodiment of the present invention.

FIG. 3 is a diagram for explaining the difference in the shape of the bar cleavage groove 13 between the first embodiment and the second embodiment.

FIG. 4 is a view for explaining an example of how to enter the cleavage lines 41 and 42 in the first and second embodiments of the present invention.

5 is a cross-sectional view showing an example of a semiconductor substrate 11 having a crystal growth layer including an active layer 12 shown in FIG. 1 (a).

FIG. 6 is a view showing a process of forming the bar cleavage groove shown in FIG. 3 (b2).

7 is a continuation of FIG. 6 and is a view showing a process of forming the bar cleaving groove shown in FIG. 3 (b2).

FIG. 8 is a diagram for explaining a conventional process when performing bar cleaving.

FIG. 9 is a diagram for explaining another example of the conventional process when performing bar cleaving.

[Description of Reference Signs] 11 ... Semiconductor substrate, 12 ... Active layer, 13 ... Bar cleavage groove,
14 ... Chip separation groove, 15 ... Triangular jig, 16 ... Ridge line, 21 ... Slope, 33 ... Apex, 35 ... Slope, 52 ... I
nP buffer layer, 53 ... n-type InP clad layer, 55
... p-type InP layer, 56 ... n-type InP layer, 57 ... p-type In
P-clad layer, 58 ... p-type InGaAs contact layer,
61 ... SiO ₂ film

Claims (11)

[Claims] 1. A semiconductor substrate, and a plurality of crystal growth layers laminated on the semiconductor substrate, wherein one of the plurality of crystal growth layers is parallel to a surface of the semiconductor substrate. An active layer formed in a linear shape having a thickness of, and an end face of the semiconductor substrate and the plurality of crystal growth layers in a direction substantially perpendicular to the linear active layer, and the plurality of crystal growth layers. A semiconductor laser device, characterized in that the upper surface of the layer is planarly removed except for a portion relatively close to the active layer. 2. The plurality of crystal growth layers are formed by growing on a (100) plane of the semiconductor substrate, and the surfaces removed by the planar shape and appearing are the semiconductor substrate and the semiconductor substrate. 2. The semiconductor laser device according to claim 1, wherein the crystal growth layers are (11/1) planes or (1/11) planes. 3. The end surface side of the removed corner is
13 μm to 25 μ from the top surface of the plurality of crystal growth layers
2. The semiconductor laser device according to claim 1, wherein m is m. 4. The semiconductor laser device according to claim 1, wherein the shape of the removed corners of the plurality of crystal growth layers on the upper surface is substantially rectangular. 5. The shape of the removed corners on the upper surface of the plurality of crystal growth layers is approximately 1 / a line symmetrical with respect to an isosceles trapezoid.
The semiconductor laser device according to claim 1, wherein the semiconductor laser device has a bisected shape. 6. The semiconductor substrate is made of InP, and each of the plurality of crystal growth layers is made of InP.
Or _{In x Ga 1- x As y P} 1-y (0 <x <1,
2. The semiconductor laser device according to claim 1, wherein 0 <y ≦ 1). 7. A step of forming, on a semiconductor substrate, a crystal growth layer including a linear active layer substantially parallel to a surface of the semiconductor substrate, and the crystal growth of the semiconductor substrate having the crystal growth layer formed thereon. Forming a groove from the layer side intermittently in a direction substantially perpendicular to the linear active layer while avoiding the active layer; and the semiconductor substrate having the crystal growth layer along the formed groove. And a step of chip-separating the semiconductor substrate having the bar-cleaved crystal growth layer in a direction substantially perpendicular to the bar-cleavage direction. . 8. The step of forming a groove, the step of forming a mask layer on the upper surface of the crystal growth layer in a pattern in which punching exists in a portion corresponding to the groove to be formed, and the formed mask layer 8. The method for manufacturing a semiconductor laser device according to claim 7, further comprising the step of etching the crystal growth layer by means of, and the step of removing the mask layer after the etching. 9. The method of manufacturing a semiconductor laser device according to claim 8, wherein in the step of forming the mask layer, the shape of the punching is substantially rectangular. 10. The semiconductor laser device according to claim 8, wherein in the step of forming the mask layer, the shape of the punching is a shape in which the long bottom sides of the isosceles trapezoid are substantially back to back. Manufacturing method. 11. The semiconductor substrate is made of InP, and each of the plurality of crystal growth layers is made of InP.
Or _{In x Ga 1- x As y P} 1-y (0 <x <1,
9. The method of manufacturing a semiconductor laser device according to claim 8, wherein 0 <y ≦ 1), and the step of etching the crystal growth layer is performed using a solvent containing hydrochloric acid as an etching solvent.